Heart rate variability, overnight urinary norepinephrine, and plasma cholesterol in apparently healthy human adults.

OBJECTIVE: The aim of this study was to assess the relationship between autonomic nervous system activity as indexed by measures of heart rate variability and overnight urinary norepinephrine, and plasma cholesterol levels in a large sample of working adults.
METHODS: The study population comprised 611 apparently healthy employees of an airplane manufacturing plant in Southern Germany. Heart rate variability was calculated as beat-to-beat intervals over the course of one 24-hour weekday measured with an ambulatory ECG recorder. Overnight urine collection and blood samples were also obtained.
RESULTS: We found an inverse association between indices of vagally-mediated heart rate variability and plasma levels of total cholesterol, low density lipoprotein (LDL), and the ratio of LDL to high density lipoprotein (HDL) that remained significant in multivariate models after controlling for relevant covariates including norepinephrine. Urinary norepinephrine was not significantly related to any measure of cholesterol in multivariate models.
CONCLUSIONS: We report here for the first time, in a large sample of healthy human adults, evidence supporting the hypothesis of a clinically relevant inverse relationship between measures of plasma cholesterol and vagally-mediated heart rate variability after controlling for sympathetic nervous system activity. This suggests an important role for the vagal control of plasma cholesterol levels in cardiovascular disease.